I just set a couple of records by using the "Check" button. I do this by guessing on the "Either/Or" clues. If a puzzle has a couple of these and I get the guess right, the puzzle just falls into place because at this point, it's just so easy. I've even set records when I get the guesses wrong.

I don't think this is right. "Check" should cost the user a large time penalty.

For example, let's have a puzzle of boys date girls have food and drinks:
"Of Ted and Alice, one had pizza and the other drank wine."

Let's set Ted to "Not Pizza." Click "Check" and the box doesn't change color. Then Alice must have had wine. Don't forget that Ted didn't date Alice and the couple who had pizza didn't have wine.

Repeat for any other "Of" clues or clues using "either".

If you get it wrong, sure, you take a time penalty for it, but not enough that you've set your ending time anywhere bad.

The key is to set the guess to "NOT". If you were to say "Ted IS pizza" and you're wrong, you suffer THREE time penalties. One for the wrong guess, and the other two because the entire Boy column and Food row are all gray when you click "Check". The upside is that you now know TWO true answers.

The "Check" button has no cost. I think it should have a very steep cost. Or maybe you only get one free "Check" and then the cost goes up for each time you click "Check".

One addition relates to the "Undo" button's capabilities. The "Undo" button seems to know when I've set something to "True" and sets all other values in the Row/Column to false. When the "Check" button finds a "True" error, it should "Undo" the "True". Thus wiping out all the Row/Column "False" values that were set automatically by the game. Any "False" values set by the user would remain and be evaluated by the "Check" feature. This would eliminate the two "True" that are given to the user by the current operation of "Check".

Maybe the program could use the "Undo" feature and roll back to the user's first error. Example: I play the game out and notice a contradiction. Because of an earlier error, the entire board is screwed. When I click "Check", the game rolls back to the earliest error and only charges me for that error (plus, of course, the use of "Check").

If you achieve your high score by cheating, or not thinking, what was the point of doing the puzzle to begin with. This is like steroids and world records, you bring everything down.

I use the check function when I'm pretty sure that my "logic" was correct, just to double check. Some of the more obscure leaps suddenly pop out at me and I'm not sure why I "know" they're true (those of you more experienced probably find them easy). Anyway, there's nothing more embarrassing that hitting the check button 27 steps later and having half the board removed.

Yeah, it's pretty demoralizing to get pretty far into a puzzle only to find out that one of your earlier steps was incorrect, thus negating all of your subsequent work. Checking prevents that from happening. Yes it probably allows some people to cheat, but who cares? I do these puzzles for fun. Besides, since there's so many puzzles, these records are relatively meaningless.

I haven't been playing as much, did something change and then change back? When I have an error upon checking, I get hit with huge penalties, I think 120 seconds per mistake. When I have one mistake, I almost always have another, so a minimum of 240 seconds penalty. I use check a lot because I hate back tracking, but my times for puzzles I make a mistake in are generally 5-10 times as much as ones that I don't. I'm not guessing. I think the penalty is plenty steep enough.